Boy that is a nice supply. I see them for $129-160 on ebay. On Thu, Mar 18, 2010 at 11:43 PM, J. L. Trantham <[email protected]> wrote:
> Just an update on the status of the 5061A. I started this thread on > January 17. > > When first turned on, it pegged the Ion Pump I meter and, at glacial speed, > seemed to be 'pumping down', as judged by measurements of voltage on pin 3 > of the A18 +3500 VDC power supply. I finally got tired of waiting and > obtained an Electrophoresis Power Supply, an E-C Apparatus EC600, that does > 0-4000 V, 0-200 W, and 0-200 mA with any one of the three limiting as > selected (thanks to Tom Frank for this suggestion, does anyone have a > schematic for this unit?). > > After several weeks, it finally pumped down to the point that the internal > power supply would allow the CS Oven to turn on but then the Ion Pump I > would peg and take forever to pump down again. After a few weeks of this > along with further 'pumping', I decided to modify the internal power supply > to allow the supply to 'cut off' the CS Oven at 80 uA instead of the > designed 40 uA by adding a 56K resistor across R6, the 75K resistor in the > A18 +3500 VDC power supply. > > This allowed the CS Oven to come on, then the Ion Pump I meter indication > would go up to the mid 40's, the CS Oven would turn off, then the pump > would pump down, and repeat the cycle. It now rests at around 30 uA on the > Ion Pump I and all meter indications are now normal with the 'turn on' > value > on the Ion Pump I meter indication at around 36. The Continuous Operation > light now comes on and, seemingly, it is working. > > However, I don't think it is, at least not yet. > > I have the 5 MHz adjusted slightly high (about 5 mHz), as compared to my > GPSDO, and the control voltage slowly increases, the frequency slowly > decreases, passing through the GPSDO frequency and then the EFC voltage > continues to increase, driving the frequency progressively lower. However, > it does not appear to 'lock' though I have not given it hours to show that. > My other CS units appear to 'lock' almost immediately once the Continuous > Operation light comes on. > > It is behaving as if the 'Loop' is not closed even though it appears to be > able to make the comparison of the 5 MHz to the CS, adjust the frequency of > the 5 MHz in the appropriate direction, but then fails to 'lock'. > > In order to get the 2nd Harmonic indication reasonable, I had to turn up > the > Loop Gain and put the A7 in 'High' gain. I am suspicious that I have other > 'adjustments' to make but have not had time to pursue this in detail. > > So, it appears that I have more work to do. However, at least as far as > the > Ion Pump goes, I think I have made progress. > > Thanks to all for the suggestions/discussion thus far and any further > suggestions would be appreciated. > > Joe > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
